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        검색결과 53

        43.
        1995.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        분말야금법으로 제조된 A6061기 입자분산강화 복합재의 열간압술가공에 있어서 압출특성에 미치는 강화입자의 종류, 빌렛특성 및 암술조건의 영향에 대하여 조사하였다. A6061기 복합재료의 열간 압술 전단 변형저항에 미치는 강화입자종류의 영향은 Si Cw > A12 O3f > A12 O3f > Si Cp의 순으로 되었으며, 모든 강화입자에서 부피분율이 증가함에 따라서 Kw값도 증가하였다. 압출조건, 강화입자의 첨가량 및 첨가입자의 평균입도에 관계없이 A12 O3p가 첨가된 복합재의 열간압출가공에 필요한 소요압력은 Si Cp의 경우보다 컸다. 압출압력은 압출 다이스 반각이 커질수록 감소하는 경향은 나타났다. 이것은 다이스 반각에 의해 생성되는 빌렛과의 접촉면적이 증가하여 전단마찰응력(m k3)이 상승하기 때문이다. 압출시 압출온도 상승은 저온에서 ~50˚C 정도 증가하였으며, 압출온도가 500˚C 이상이 되면 압출재 표면에 극심한 tearing이 발생하였다. 강화입자의 첨가량이 증가할수록 이 현상은 더 심하게 되었다.게 되었다.
        4,000원
        45.
        1994.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        대두유를 튀김유로 사용하여 french fried potato를 185℃에서 제조하면서 84시간 튀김한 후 aluminium alloy (물, silicone, manganese, porous aluminium carrier을 함유)를 처리한 감자튀김유와 대조구의 물리화학적변화를 측정하였다. 물리화학적 변화의 척도로는 극성지질, 중합체의 함량, 공액이중산가 및 유리지방산가를 사용하였다. Aluminium alloy를 처리한 시료는 대조구에 비해 극성지질 및 중합체 형성을 크게 억제하였으며 공액이중산가 및 유리지방산가의 증가 억제에는 영향을 주지 않았으며 유리지방산가의 경우 오히려 촉진되는 결과를 보였다 따라서 튀김유에 대한 aluminium alloy의 처리는 유리지방산이나 공액이중산의 형성억제보다는 극성지질 및 중합체의 형성억제에 효과적임을 알 수 있었다.
        4,000원
        46.
        1994.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        여러가지 화학 조성을 갖는 aluminium titanate mullite복합제는 AI2O3분말을 알콜 분산용액에서 Si(OC2H5)4과 Ti(OC2H5)4의 단계적인 가수 분해로 합성되었다. Mullite함량이 20-50vol%인 소결체(1600˚C/2h)는 비교적 높은 강도와 낮은 열팽창 계수를 갖는 aluminium titanate를 개발할 수 있는 가능성을 보였다. 이와 같은 결과는 mullite로 인한 aluminium titanate의 입자 크기의 억제와 미세균열에 의하여 얻어졌다. aluminium titanate의 함량이 70-80vol% 복합재료는 우수한 열충격 저항성을 지녔으며 상온 강도는 31-45MPa이었다. 열충격 저항성, 영률, sound velocity화 열팽창 계수가 연구되었다.
        4,000원
        48.
        2013.11 서비스 종료(열람 제한)
        The estimated that 114 million units of fluorescent lamp are sold every year, and that 70% or more spent fluorescent lamps (SFLs) are generated at business sites. According to Korea Lighting Recycling Corporation, recycled amount of SFLs selected as EPR (Extended Producer Responsibility) items from 2004 has been improved from 35,250,000 units in 2010 to 37,950,000 units in 2011, which recorded the greatest amount. Based on the year 2011, SFLs have been recycled by 31.5%, but their recycled rate is insufficient yet, compared to the recycling rate of metal cans or glass bottles, which are about 80%. The base cap of SFLs as a raw material was used in this experiment. Base cap contains an insulation sieve plate, aluminum cap, copper terminal, tempered glass, filament, and copper/iron mixed wire that goes through this glass. In order to protect a filament that is made up of tungsten for the electricity to flow, circular plate consisted of iron encloses the filament. Separating apparatus of SFL base cap used in this experiment is a device which has used impact crushing technique using hammer, screen separation and magnetic separation for the purpose of recovering aluminum, copper and iron contained in SFL. Impact hammer crusher, a device that separates aluminum from other materials by hammer impaction on the base cap that is separated by end-cutting, causes a significant reduction for other materials to be included in the collectible materials by separating aluminum, copper and iron from the base cap by using hammer crusher at 3 stages. Iron was collected by using a magnetic separation unit and the collectible materials were separated into aluminum with larger particles, and glass and other materials with smaller particles by screen separation. The separation performance was estimated for the 3 stages of hammer crusher unit to recover aluminum from the base-cap of SFLs and the separation performances are 94% at the 1st stage, 97% at the 2nd stage, and 98% at the 3rd stage, respectively.
        49.
        2007.12 KCI 등재 서비스 종료(열람 제한)
        일반적으로 선박 및 해양구조물에서 사용하고 있는 고강도 알루미늄 재료들은 일반 강재에 비해서 많은 이점들을 가지고 있다. 이러한 알루미늄 재료들은 여러 분야에 걸쳐서 폭넓게 사용되고 있으며, 특히, 초고속 선박의 선체와 갑판부에 많이 이용되어지고 있고, 교량구조물에 사용되는 박스 거더, 그리고 해양구조물의 갑판부와 선측구조에도 널리 이용되고 있다. 이러한 알루미늄 구조는 전체적인 구조부재의 중량을 감소하게 하면서 선속의 증가를 가져온다. 일반적인 강구조물의 응력-변형률 관계와 비교하여 보면, 용접가공에 의하여 발생되는 열영향부의 존재로 인하여 상당히 다르게 나타난다. 왜냐하면, 강구조물에 비해 열전도율이 높아서, 열영향부(heat affected zone, HAZ)의 영향이 크게 작용하기 때문이다. 본 논문에서는 종방향 압축하중을 받는 알루미늄 보강 판넬의 최종강도 특성에 대하여, 열영향부의 범위를 변화한 유한요소해석을 통하여, 열영향부의 범위와 파굴 및 최종강도 거동의 관계에 대해서 고찰하였다.
        50.
        2000.02 KCI 등재 서비스 종료(열람 제한)
        Laboratory experiments were performed to investigate the effects of various factors on the phosphorus removal by electrolysis with aluminium electrodes. The efficiency of phosphorus removal increased with increasing of voltage applied, surface area of electrodes and electrolyte concentration, and decreasing of electrode distance. The phosphorus removal was not affected by the connection number of an electric circuit. The amount of aluminium ion eluted from electrodes according to Faraday's law was 4.47 ㎎ and the Al/P mole ratio was 2.14 at the electric current value of 20 ㎃.
        51.
        1999.12 KCI 등재 서비스 종료(열람 제한)
        The fundamental experiments on the phosphorus removal from water were carried out by the batch and continuous reactors which used aluminium and copper plate. In this systems, the phosphorus was removed by aluminium ion generated with the electrochemical interaction (pitting corrosion) of aluminium and copper. In the batch experiments, the efficiencies of phosphorus removal increased when the surfaces of aluminium and copper plate were brushed. The phosphorus removal by aluminium ion was affected the copper plate and NaCl in this system. The optimal pH values were 5 and 6 for the phosphorus removal. The efficiency of phosphorus removal increased with increasing NaCl concentration, surface area of aluminium and copper plate. The CuSO4·5H2O instead of copper plate could be used as Cu source. The effluent PO4-P concentration as low as 2㎎/ℓ could have been obtained during the continuous experiment at HRT of 48 hrs.
        52.
        1996.12 KCI 등재 서비스 종료(열람 제한)
        The toxic effects of aluminium (Al) on growth, chlorophyll content, δ-aminolevulinic acid dehydratase (ALAD) activity and anatomy of root and shoot were investigated in 7-day-old azuki bean (Vigna angularis) seedlings. Significant depressions in root elongation was observed in the low concentrations of Al (50, 100 ㎛) and increasing Al concentrations caused a sharp decline of root and shoot growth. The degree of inhibition was dependent upon Al supply. Exposure to 50 ㎛ Al or more inhibited root elongation within 1 day. In the 50 ㎛ Al treatments, a recovery of root growth was seen after 7 days exposure. In contrast, lateral root initials was little affected by Al exposure. Al toxicity symptoms and growth responses were more well developed in the roots than in the shoots. Analysis of Al localization in root cells by hematoxylin staining showed that Al entered root apices and accumulated in the epidermal and cortical cells immeadiately below the epidermis. There was a good positive correlation between the level of chlorophyll and ALAD activity. Increasing Al concentrations caused a decrease in total chlorophyll contents, accompanied by proportional changes in ALAD activity, suggesting a coordinated reduction of a photosynthetic machinery. Al exerted specific influence on the morphology of root and shoot. At higher concentrations of Al the roots induced drastic anatomical changes. The epidermal cells were disorganized or destructed while the cortical cells exhibited distortion of cell shape and/or disintegration. The diameter of root and transectional area of cortical cells decreased considerably with Al treatment. In the shoot Al also enhanced reduction of diameter of shoot and cell size. Gross anatomy of leaves treated with Al did not differ significantly from the controls, except for fewer and smaller chloroplast. Our results indicate that toxic effect of Al appear to be manifested primarily in roots and secondarily on shoots, and changes in root morphology are related to changes in the root growth patterns. Results are further discussed in relation to the findings in other plant species, and it is concluded that Al causes morphological, structural and, presumably, functional damage to the roots of the species investigated.
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